Conventionally, when descending from elevated positions such as a helicopter, via a rope, in which users wish to rapidly engage, safely descend, and rapidly disengage from the rope, so called “fast-ropes” have been used. These conventional ropes are usually 1.5 to 2.0 inches in diameter, and are constructed of a variety of synthetic fibers. Generally, such fast-ropes are of a braided construction, providing a strong, flexible rope.
In practice, the user of a fast-rope attaches the rope to a secure location and unfurls it, spanning the altitude that the user wishes to descend. The user embraces the rope with his body and slides down the rope, attempting to control the rate of his descent by squeezing the rope at his feet, thighs, and hands. This squeezing of the rope creates friction between the rope and the user, thereby converting the kinetic energy created by the descent along the rope to heat energy, and consequently controlling his descent despite gravity's influence to accelerate his body toward the ground.
However, such conventional fast-ropes present various problems related to control of descent. Firstly, conventional fast-ropes are incompressible by a human hand, and thus require a user to possess relatively high hand strength (i.e., require high squeezing force) to create sufficient friction to control descent. This limitation of the amount of squeezing force the user can apply to the rope disallows some users from creating the friction needed to control the descent of their bodies.
Further, today, many fast-rope users are descending fast-ropes with more weight attached to their body than in previous years. For example, soldiers now frequently carry an increased amount of gear for extended deployment in the field, resulting in additional weight to control during descent. As mentioned above, the inability to create sufficient friction results in loss of control during descent, and is only exacerbated by the additional weight now frequently carried.
Consequently, users of fast-ropes now frequently land on the ground at unsafe velocities, resulting in injuries such as fractured bones, twisted ankles, internal injuries and, in severe cases, even death. At the minimum, users frequently experience burned hands from their attempts to apply maximum friction to the rope. In some circumstances, when descending onto an elevated surface via a helicopter, the helicopter (and consequently the rope) drift away from the elevated structure during descent, causing the rope to hang in the air some altitude above the ground and/or the elevated structure. Some users have been unable to halt their descent on the rope at this time, and have instead slid off of the end of the rope at an unsafe elevation above the ground or elevated structure, resulting in severe injuries.
Of those users who can provide the additional force necessary to maintain a safe descent speed, the additional friction needed to control descent translates into more heat generation, which raises the temperature of the user's body at the contact points. Many users experience burning of the hands, even while wearing improved heat protective gloves. Of even more concern is a subset of users who, reflexively, release the rope during descent when experiencing the burning sensation caused by friction, resulting in the user free falling the remaining altitude to the ground.
As discussed above, conventional fast-rope assemblies are, effectively, incompressible, prohibiting the user from altering force through the movement or displacement of his hands. The primary method of controlling descent is to alter descent speed through varying the force applied to the rope (while not displacing his hands from their original position). Human motor skills are optimized to control things in displacement regimes more effectively than force regimes (e.g. “squeezing). Force controls are more awkward for the user to manipulate than displacement controls. Conventional fast-ropes allow only force control techniques to control descent speed, and hence create difficulty for the user in controlling his descent.
In view of the deficiencies of the conventional fast ropes, as described above, it is an object of the present invention to provide a radially compressive rope assembly which allows a user to make a controlled descent without requiring excessive grip strength.
It is a further object of the present invention to provide a radially compressive rope assembly whose structure results in the avoidance of high frictional heat generation during descent, thereby avoiding the danger of burning, as encountered with conventional fast ropes.
It is a further object of the present invention to provide a radially compressive rope assembly which may be weighted at desired locations, so as to alter the weight profile of the rope and provide stability where needed.
It is a further object of the present invention to provide a radially compressive rope assembly that allows the user to control descent in the displacement regime.